Image analysis – Applications – Manufacturing or product inspection
Reexamination Certificate
1999-02-01
2002-04-30
Johns, Andrew W. (Department: 2621)
Image analysis
Applications
Manufacturing or product inspection
C359S196100, C359S362000
Reexamination Certificate
active
06381359
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a bonding apparatus for bonding two parts such as a semiconductor chip and a substrate, lead frame or tab tape and more particularly to an optical detection device for detecting positional discrepancies between the two parts so as to make an alignment thereof.
2. Prior Art
For example, the apparatus disclosed in Japanese Patent Application Publication (Kokoku) No. H6-28272 is known as a conventional bonding apparatus that is equipped with an optical detection device. This optical detection device is comprised of an optical probe which is moved between two parts positioned so as to face each other for being bonded, first and second optical means which focus respective images of the two parts from the optical probe, and an image pickup means which pick up the images focused by the first and second optical means. The two parts are aligned based upon the detection results obtained by the optical detection device, and then bonding is performed for these two parts.
This apparatus will be described in more detail with reference to
FIGS. 4 through 7
.
As shown in
FIG. 4
, a substrate
1
is positioned and held by a substrate chuck
3
which is installed on an XY table
2
, and a semiconductor chip
4
is held by a chip chuck
6
disposed on the bonding head
5
. After the semiconductor chip
4
is moved to a point above the substrate
1
, the bonding head
5
is lowered, and the chip
4
is bonded to the substrate
1
. Here, the bonding head
5
is disposed on a supporting element
7
in a manner that the bonding head
5
can be raised and lowered. An optical detection device
10
is installed on an XY table
11
and moved between the substrate
1
and the semiconductor chip
4
. The XY table
11
is mounted on the supporting element
7
, and the optical detection device
10
has an optical probe which will be described later. Images of the substrate
1
and semiconductor chip
4
obtained by the optical detection device
10
are synthesized by an image synthesizing circuit
12
and displayed on a TV monitor
13
.
As shown in
FIG. 5
, the optical detection device
10
comprises an optical probe
20
which is moved between the substrate
1
and the semiconductor chip
4
, first and second optical means
25
A and
25
B and first and second illumination means
30
A and
30
B which are associated with the optical probe
20
, and first and second image pickup means
35
A and
35
B for picking up the images which are of the substrate
1
and semiconductor
4
and focused by the first and second optical means
25
A and
25
B.
As seen from
FIGS. 4 and 5
, the optical probe
20
includes a first image acquisition prism
21
A and a second image acquisition prism
21
B. The first image acquisition prism
21
A causes a 90-degree rotation of a first image of the surface of the semiconductor chip
4
, e.g., an alignment mark applied to the semiconductor chip
4
, a bump on the semiconductor chip
4
or the like. The second image acquisition prism
21
B causes a 90-degree rotation of a second image of the surface of the substrate
1
, e.g., an alignment mark applied to the substrate
1
or a pad on the substrate
1
in a different direction from the first image or the like. The optical probe
20
further includes a first optical system introduction prism
22
A and a second optical system introduction prism
22
B which are respectively provided on both sides of the first and second image acquisition prism
21
A and
21
B. The first image obtained by the first image acquisition prism
21
A is reflected by the first optical system introduction prism
22
A which causes a 90-degree reflection of the first image and then enters into a first optical means
25
A. Likewise, the second image obtained by the second image acquisition prism
21
B is reflected 90 degrees by the second optical system introduction prism
22
B and enters into a second optical means
25
B.
The above-described first and second illumination means
30
A and
30
B are perpendicularly disposed in respective positions between the first and second optical means
25
A and
25
B and first and second image pickup means
35
A and
35
B. Illuminating light beams produced by the first and second illumination means
30
A and
30
B are respectively projected (as projected light beams
32
A and
32
B) in the directions of the first and second optical means
25
A and
25
B by first and second half-mirrors
31
A and
31
B. These projected light beams
32
A and
32
B are respectively projected on the semiconductor chip
4
and substrate
1
via the first and second optical means
25
A and
25
B, first and second optical system introduction prisms
22
A and
22
B and first and second image acquisition prisms
21
A and
21
B.
The projected light
32
A strikes the semiconductor chip
4
, and thus becomes reflected light
33
A. A first image (of the semiconductor chip
4
) based on this reflected light
33
A passes through the first image acquisition prism
21
A, first optical system introduction prism
22
A, first optical means
25
A and first half-mirror
31
A and is picked up by the first image pickup means
35
A. The projected light
32
B strikes the substrate
1
, and thus becomes reflected light
33
B. A second image (of the substrate
1
) based on this reflected light
33
B passes through the second image acquisition prism
21
B, second optical system introduction prism
22
B, second optical means
25
B and second half-mirror
31
B and is picked up by the second image pickup means
35
B.
The first image of the downward-facing surface of the semiconductor chip
4
is caused to be incident on the first image acquisition prism
21
A, and the second image of the upward-facing surface of the substrate
1
is caused to be incident on the second image acquisition prism
21
B. Consequently, if the first and second images produced by the first and second image acquisition prisms
21
A and
21
B were merely reflected by the first and second optical system introduction prisms
22
A and
22
B, the images picked up by the first and second image pickup means
35
A and
35
B would not be in a relationship suitable for superimposition with the surface positions arranged in the corresponding image positions. Accordingly, as shown in
FIGS. 4 and 6
, the first image which is picked up by the first image pickup means
35
A is reflected by an inverting mirror
40
so that a mirror image is formed and then picked up by the perpendicularly installed first image pickup means
35
A.
The first and second images picked up by the first and second image pickup means
35
A and
35
B are synthesized by the image synthesizing circuit
12
shown in
FIG. 5
, and the synthesized images are shown on a TV monitor
13
. Then, the XY table
2
is driven so that any positional discrepancies between the two images are corrected, thus aligning the two images. Afterward, the XY table
11
is driven so that the optical probe
20
of the optical detection device is withdrawn from between the substrate
1
and the semiconductor chip
4
. Then, the bonding head
5
is lowered so that the semiconductor chip
4
is bonded to the substrate
1
.
In the prior art described above, in order to place the two images in a relationship which is suitable for superimposition with surface positions arranged in the corresponding image positions, the first image is converted into a mirror image by an inverting mirror
40
. Since the first and second image acquisition prisms
21
A and
21
B and first and second optical system introduction prisms
22
A and
22
B are provided in front of the first optical means
25
A, there is no space to install an inverting prism
40
in this area. For this reason, the inverting mirror
40
is installed between the first optical means
25
A and first image pickup means
35
A as seen from FIG.
7
.
As seen from the above, the prior art optical detection device
10
is designed so that the first image of the first optical means
25
A is reflected by the inverting mirror
40
, and this ref
Johns Andrew W.
Kabushiki Kaisha Shinkawa
Koda & Androlia
Patel Kanji
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